After having a "no start" problem from a vacuum line coming off the canister I decided to bite the bullet and pull the whole thing off. After reading everything I could find about it I pulled the canister and capped off the electronic valve. Then I decided to see if I even needed to keep the valve. I unplugged it from the harness and the bike fired right up. There was no service light or any other indication it was unplugged. I removed the valve and capped the T fitting between the throttle bodies. There was a nice little rubber band type wire tie right near the harness plug so I put the plug into it to keep it from flopping around. As for the vent line, routing it to the bottom of the bike where it will go under water on a regular basis seemed dumb considering that it sucks air into the fuel tank. I unplugged the long section of hose and just left the check valve tied to the subframe where it was. I figured having it inside the plastic will keep it reasonably clean and dry unless the whole bike goes under in which case I will have bigger problems.

scroll all the way down to the "comments" section.
The new F700GS and F800GS may have a diminished fuel capacity..............
We need someone with a new bike to pop off the seat and see what's there .............
I have not paid attention to the published fuel capacity of the new models ... is it different?

With regard to the 2013 model F800gs:
CharcoalCanister looks to be about 20 fluid ounces in volume. black plastic can, one 8mm drain port at bottom one each 6mm and 8mm top ports.
The entire motorcycle seems to have been built up around the charcoal can. It is at the approximate center point of the bike, and seems to be unremovable, although it occupies the PERFECT spot for a large canister style fuel filter.